The homestead forests of Bangladesh occupy 0.27 million hectares (10% of the total forested area) and have potential to store carbon (C) and conserve biodiversity. Small scale forestry practices, however, are lacking reliable estimation of C stocks and tree species diversity. This may hinder successful implementation of REDD + and similar mechanisms as they concentrate on large-scale forests. This study aimed to estimate the above- and below-ground carbon stocks in homestead forests of Maheshkhali Island in Bangladesh and how tree species diversity and stand structural variation affect these C stocks. We randomly surveyed a total of 239 homestead forests in the hillside, beachside, and inland in 2019. Tree biomass C stocks were 48–67% greater in the inland and hillside forests than in the beachside due to significantly greater stand density, basal area, tree diameter. In total we found 52 tree species, but most abundant species in the inland and hillside forests, Mangifera indica, Samanea saman, and Artocarpus heterophyllus stored the most C in tree biomass. Greater tree species richness and diversity index in the inland and hillside forests indicated greater above- and below-ground tree biomass C stocks. An increase in tree species richness and diversity index by one unit was found to increase the tree biomass C stock by 22 and 30 Mg C ha−1, respectively. The total soil C stock was also affected by tree species diversity, stand density, and their interaction with soil properties. Total soil C stocks were greatest (51 Mg ha−1) in the inland forests, having also the greatest stand density and tree species richness. C stock in soil surface was greatest in the hillside forests due to the greatest litterfall, but the average share of litterfall from the total biomass C was only 0.1%. Homestead forest ecosystems could store 96 Mg C ha−1 in total, which can contribute to climate change mitigation by generating C credits for small-scale homestead forests owners. Above- and below-ground tree biomass C stocks were found to correlate with tree species diversity, which may also contribute to biodiversity conservation in the REDD + in Bangladesh and countries alike.

中文翻译：

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孟加拉国南部Maheshkhali岛树种多样性和林分结构对家园森林碳储量的影响

孟加拉国的家园森林占地27万公顷（占森林总面积的10％），具有储存碳（C）和保护生物多样性的潜力。然而，小规模的林业实践缺乏对碳库和树木物种多样性的可靠估计。这可能会阻碍REDD +和类似机制的成功实施，因为它们专注于大型森林。这项研究旨在估计孟加拉国Maheshkhali岛家园森林中的地上和地下碳储量，以及树木物种多样性和林分结构变化如何影响这些C储量。我们在2019年对山坡，沙滩和内陆的239个家园森林进行了随机调查。由于林分密度显着提高，内陆和山坡森林的树木生物量碳储量比沙滩和内陆森林高48-67％，基础面积，树木直径。我们总共发现了52种树木，但在内陆和山坡森林，印度芒果，萨曼娜萨曼（Sananea saman）和面包果（Artocarpus heterophyllus）中，最丰富的树木存储了树木生物量中的C。内陆和山坡森林中更大的树木物种丰富度和多样性指数表明，地上和地下树木生物量碳储量更大。发现树木物种丰富度和多样性指数增加了一个单位，树木生物量碳库分别增加了22 Mg C ha-1和30 Mg C ha-1。土壤总碳储量还受到树木物种多样性，林分密度及其与土壤特性的相互作用的影响。内陆森林土壤碳储量总量最大（51 Mg ha-1），林分密度和树木物种丰富度也最大。由于凋落物数量最多，山地森林土壤表面的碳库最大，但凋落物占总生物量碳的平均份额仅为0.1％。宅基地森林生态系统总共可以存储96 Mg C ha-1，这可以通过为小型宅基地森林所有者产生C信用额度来缓解气候变化。发现地上和地下的树木生物量碳库与树木物种多样性相关，这也可能有助于孟加拉国和其他国家的REDD +的生物多样性保护。